Different Scale Experiments of High Velocity Penetration With Concrete Targets

In this study, two different scale projectile high velocity penetration experiments with concrete targets that had an average compressive strength of 35 MPa were conducted in order to find the velocity limits and nose erosion properties. We conducted the penetration experiments for the small-scale (48 mm diameter, 195 mm long, 2 kg) and the large-scale (144 mm diameter, 680 mm long, 50 kg) ogive-nose projectiles with the hard steel 4340 whose dynamic compression strength is 2.2 GPa. A 100-mm-diameter powder gun was used to launch the five tests of the 2 kg projectiles with striking velocities between 1100 m/s and 1600 m/s and a 320-mm-diameter Davis gun was used to launch the two tests of the 50 kg projectiles with striking velocities 1100 m/s and 1300 m/s. The experimental results showed that the nose material was missing, indicating an apparent eroding process when the striking velocity exceeded 1400 m/s, where the rigid body penetration made a transition into the elastic-plastic hydrodynamics regime and penetration depth begin to decrease when the striking velocity exceeds 1400 m/s. Furthermore, nose changes and mass loss due to nose erosion did not significantly affect the penetrating ability before rigid body penetration made a transition into the hydrodynamic regimes. In addition, nose erosion was analyzed with SEM surface microstructures, and the SEM image showed that the mass loss of projectiles was due to the shear cracks preceded by adiabatic shear bands.

Semi-Infinite Target Penetration by Ogive-Nose Penetrators: ALEGRA/SHISM Code Predictions for Ideal and Nonideal Impacts

The physics of ballistic penetration mechanics is of great interest in penetrator and countermeasure design. The phenomenology associated with these events can be quite complex, and a significant number of studies have been conducted ranging from purely experimental to “engineering” models based on empirical and/or analytical descriptions to fully coupled penetrator/target, thermomechanical numerical simulations. Until recently, however, there appears to be a paucity of numerical studies considering “nonideal” impacts (Goldsmith, 1999, “Non-Ideal Projectile Impact on Targets,” Int. J. Impact Eng., 22, pp. 95–395). The goal of this work is to demonstrate the SHISM algorithm implemented in the ALEGRA multimaterial arbitrary Lagrangian Eulerian code (Boucheron, et al., 2002, ALEGRA: User Input and Physics Descriptions, Version 4.2, SAND2002-2775, Sandia National Laboratories, Albuquerque, NM). The SHISM algorithm models the three-dimensional continuum solid mechanics response of the target and penetrator in a fully coupled manner. This capability allows for the study of nonideal impacts (e.g., pitch, yaw, and/or obliquity of the target/penetrator pair). In this work predictions using the SHISM algorithm are compared with previously published experimental results for selected ideal and nonideal impacts of metal penetrator-target pairs. These results show good agreement between predicted and measured maximum depths-of-penetration (DOPs), for ogive-nose penetrators with striking velocities in the 0.5–1.5 km/s range. Ideal impact simulations demonstrate convergence in predicted DOP for the velocity range considered. A theory is advanced to explain disagreement between predicted and measured DOPs at higher striking velocities. This theory postulates uncertainties in angle-of-attack for the observed discrepancies. It is noted that material models and associated parameters used here were unmodified from those in literature. Hence, no tuning of models was performed to match experimental data.

PENETRATION CONCRETE TARGETS EXPERIMENTS WITH NON-IDEAL & HIGH VELOCITY BETWEEN 800 AND 1100M/S

In this paper, three types of projectiles were designed, which are based on the physical mechanism of high-speed penetrating into concrete targets. The three types of projectiles are ogive nose followed by cylinder, cone and grooved cone shank respectively, which are made of 30 CrMnSiNi2A with the yield strength 1570MPa. The unconfined compressive strength of concrete target for test is 50MPa. Seven experiments for striking velocities between 800 and 1100m/s were conducted. The experiments showed that the projectiles of cone and grooved cone shank have better penetration performances and the penetration channels were very straight. Compared with the cylinder shank projectiles, the cone and grooved cone shank projectiles are more effective under the condition of high velocity penetrating into complex geological materials as concrete or rock.